A lighter is most useful for a smoker, and numerous kinds of lighters have of course been on the market, both cheap and expensive. Nowadays, there is a growing tendency that inexpensive simple disposable lighters are popular, and the reasons are the following.
1. An expensive lighter is liked by some rich people for its beautiful appearance, but is costly to replace if lost.
2. A can of butane has to be kept at home in order to fill an expensive light when its gas has been used up, and this can be inconvenient.
3. A simple cheap lighter can simply be discarded and replaced after the gas is used up, and if lost by carelessness there is no feeling of serious loss.
Generally speaking, a form of simple lighter in use today, as shown in FIG. 1, comprises a butane well 10 containing butane as the combustible liquid, a gas valve 13 on a base 12 on the upper face of the butane well 10, a gas tube 131 communicating the bottom of the valve 13 with the interior of the butane well 10, a gas adjuster 132 beside the valve 13, a valve opening plate 14 extending to one side of the valve 13, supports 121 extending upwardly from both sides of the base 12, a striker wheel 15 rotatably mounted between the two supports 121, and a flint 16 resiliently urged against the bottom of the striker wheel 15 by means of a spring.
The striker wheel 15 has to be pushed by the user's thumb to rotate and rub against the flint 16 so as to generate sparks. The valve opening plate 14 is pushed down by the thumb at the same time so as to let the gas flow out of the gas valve 13 and be ignited by the sparks. The plate 14 must be kept pushed down to maintain the gas flow from the well 10 whilst the lighter is used. Such an arrangement is advantageously simple, but has the following drawbacks.
1. Fast heat transmission. The thumb is directly exposed to the increasing temperature of the valve opening plate which is made of metal and located very near the striker wheel, and often becomes unacceptably hot causing the user prematurely to release the plate to avoid discomfort.
2. Injury possible. The thumb can be injured whilst rotating the knurl-faced striker wheel 15 which has its underside continuously engaged with the flint 16 and is often quite stiff to rotate.
3. Hard to ignite. Both the striker wheel 15 and the gas opening plate 14 have to be pushed almost simultaneously for successful ignition, and it is awkward to manage to complete both actions at the same time, since the striker wheel 15 is hard to rotate owing to its engagement with the flint and the user's anxiety about injuring the thumb by applying too much force.
4. Inadvertent release of gas. As the gas opening plate 14 is exposed and a lighter is often kept in a pocket, especially a trouser pocket, the plate 14 may be depressed carelessly to allow unignited gas to escape freely from gas well, or may become damaged and not subsequently work properly.